Method of forming a spring-like fire strip

Abstract

A fire strip for a suspended grid ceiling has an inner spring steel web having a slightly arcuate cross section, and an outer web of soft steel wrapped around the inner web. A finished strip is formed by bending the strip normal to the strip body at both ends. When the ends are bent, a spring-like, yieldable, upwardly curved arch is formed which fits snugly against a panel when in place in a ceiling.

I claim: 
     
       1. The method of making a fire strip, including a strip body, having an under side and an upper side, and first and second ends, for a grid ceiling for supporting panels, and having (a) an inner web of spring steel on the upper side of the strip and having a preformed arcuate cross section extending concavely upwardly, and having a top, a bottom, and side edges,   (b) an outer web of soft steel disposed at said bottom of the inner web on the under side of the strip and having edge portions wrapped around the side edges of the inner web and bent to lie along the top of the inner web,   (c) end portions at both ends of the strip bent upwardly substantially normal to the strip body, and   (d) fastening means on said end portions for securing the ends of the strip to grid members; wherein the body of the strip has an upwardly extending, spring-like, yieldable arch; comprising     (a) continuously forming the inner web from a flat and rectangular cross section into said arcuate cross section,   (b) continuously wrapping and bending the outer web around the inner web thereby forming a continuous strip,   (c) cutting the resultant continuous strip into given strip lengths, and   (d) bending portions of the strip lengths at both ends normal to the strip to form an upwardly extending, yieldable, spring-like arch.   
     
     
       2. The method of claim 1 wherein the strip end portions are formed into fasteners for securing the strip to grid members. 
     
     
       3. The method of making a metallic strip for a suspended grid ceiling, comprising: (a) continuously forming an inner web from a flat and rectangular cross section of spring steel into an arcuate cross section,   (b) continuously wrapping and bending an outer web of soft steel around the inner web thereby forming a continuous strip,   (c) cutting the resultant continuous strip into given strip lengths, and   (d) bending a portion of the strip lengths at both ends normal to the strip to form an upwardly extending, yieldable, spring-like arch.   
     
     
       4. The method of claim 3 wherein the strip end portions are formed into fasteners for securing the strip to grid members.